HR: 0800h
AN: A21C-0645    [Abstracts]
TI: The Microphysical and Optical Properties of Saharan Dust as Observed During NAMMA
AU: * Slusher, D L
EM: dslusher@coastal.edu
AF: Coastal Carolina University, P.O. Box 261954, Conway, SC 29528-6054, United States
AU: Chen, G
EM: gchen@nasa.gov
AF: NASA Langley Research Center, 21 Langley Blvd., Hampton, VA 23681, United States
AU: Anderson, B E
EM: bruce.e.anderson@nasa.gov
AF: NASA Langley Research Center, 21 Langley Blvd., Hampton, VA 23681, United States
AU: Thornhill, K L
EM: kenneth.l.thornhill@nasa.gov
AF: NASA Langley Research Center/SSAI, 21 Langley Blvd., Hampton, VA 23681, United States
AU: Winstead, E L
EM: e.l.winstead@larc.nasa.gov
AF: Science Systems and Applications, Inc. (SSAI), 1 Enterprise Pwky, Suite 200, Hampton, VA 23666, United States
AU: Gleicher, K J
EM: glki0401@stcloudstate.edu
AF: St. Cloud State University, 720 4th Avenue South, St. Cloud, MN 56301, United States
AU: Diskin, G S
AF: NASA Langley Research Center, 21 Langley Blvd., Hampton, VA 23681, United States
AU: Nenes, A
EM: nenes@eas.gatech.edu
AF: Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332-0340, United States
AB: Recent analysis of satellite observations showed strong links between the variabilities of North Atlantic tropical cyclone (TC) activities and dust present in Saharan air layers (SALs). SALs are typically characterized by a layer of dry and warm air with dust. It has been hypothesized that that SALs play a significant role in suppressing the development of tropical cyclones. To better understand the interactions between SAL and TC development, NASA Africa Monsoon Multidisciplinary Analysis (NAMMA) conducted airborne observations of SAL and Saharan dust during missions flown from Cape Verde during the summer of 2006. A summary will be presented of in-situ observations of Saharan dust microphysical and optical properties as well as the vertical distributions of the dust layers. A total of ~60 individual dust layers were observed during the NAMMA airborne field campaign. The observed average dust volume loading ranged from 10 to 50 μm³ cm^-3, with a typical volume mean diameter of 2 μm. The observed scattering coefficient at 550 nm varied from 50 to 200 Mm^-1. Estimated mass scattering efficiencies ranged from 0.7 and 1.0 m² g^-1. The observed dust absorption was typically very weak, with SSA values at 550 nm around 0.99. A closure assessment suggests that ~ 85% of the observed scattering can be explained by the predictions derived from observed size distributions. Also presented are the evolution processes of dust microphysical and optical properties as being transported across the Atlantic. Finally, model simulations will be discussed in terms of the Saharan dust effect on the cloud droplet size distributions.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0365 Troposphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting